This invention relates to a toner dispensing device, and more particularly to a device for supplying toner to an apparatus for developing latent electrostatic images.
In conventional toner dispensing devices, the toner is supplied at a constant rate, for example, by rotatable spirally threaded rollers as disclosed in U.S. Pat. No. 4,089,600 to Ito et al, or by a toner supplying plate which is reciprocally movable and has supply openings therein, as disclosed in U.S. Pat. No. 4,122,981 to Takeuchi et al. Various other supplying means are also known.
In recent years, when using the above-described developing apparatus in electrophotographic copying machines which are adapted for high-speed quantity reproduction which causes an increase in toner consumption, it has become common practice to use a larger size toner storage chamber having increased capacity for the toner dispensing device to reduce the frequency with which toner must be supplied to the storage chamber. However, the increased quantity of toner in the chamber at any given time will compact the toner in the lower portion of the chamber due to the weight of the toner, with the resulting tendency that a larger amount of toner will be supplied from the lower portion of the chamber to the developing apparatus by the supplying means. On the other hand, when the quantity of the toner within the chamber is reduced, the toner in the lower portion of the chamber becomes less affected by the weight of the toner and remains at a lower density than otherwise. The amount of toner supplied is then likely to decrease.
Briefly, an increase in the capacity of the toner storage chamber entails the drawback that the toner supply varies markedly with variations in the quantity of toner accommodated in the chamber. This adversely affects the function of the developing apparatus itself. Therefore, it is imperative to overcome this drawback in the toner dispensing devices by some means. For example, the toner dispensing device disclosed in the specification of U.S. Patent 4,122,981 described above is provided with a pivotable stabilizing plate disposed within the toner tank and having a plurality of openings for passing the toner therethrough.